patch to do number of certifications required be greater
than x. node_paths is incremented not only when node_flow
is incremented but also when it is found that there is a
path [any path] to the supersink. could be implemented as
returning node_flow[i] + node_sink[i]. not entirely
confident about whether this Does The Right Thing!

int *node_sink; /* 1 if there is flow from this node to
the supersink */
+ int *node_paths; /* number of paths to the node */
int *node_flow; /* total flow through the node */
int *node_in_degree;
int *node_in_degree_max;
@@ -100,6 +101,7 @@